As a scientific discipline, ecology is almost exactly a hundred years old. The concept emerged for the first time in 1868 when the German biologist, Ernst Haeckel, in his Natural History of Creation, proposed giving this name to a sub-discipline of zoology—one which would investigate the totality of relationships between an animal species and its inorganic and organic environment. Compared with the present state of ecology, such a proposal suggests a comparatively modest programme. Yet none of the restrictions contained in it proved to be tenable: neither the preference given to animal species over plant species, nor to macroas opposed to micro-organisms. With the discovery of whole ecosystems, the perspective which Haeckel had had in mind became redundant. Instead there emerged the concept of mutual dependence and of a balance between all the inhabitants of an ecosystem, and in the course of this development the range and complexity of the new discipline have grown rapidly. Ecology became as controversial as it is today only when it decided to include a very particular species of animal in its researches—man. While this step brought ecology unheard of publicity it also precipitated it into a crisis about its validity and methodology, the end of which is not yet in sight.

Human ecology is, first of all, a hybrid discipline. In it categories and methods drawn from the natural and social sciences have to be used together without this in any way theoretically resolving the resulting complications. Human ecology tends to suck in more and more new disciplines and to subsume them under its own research aims. This tendency is justified not on scientific grounds but because of the urgency of ecology’s aims. Under the pressure of public debate ecology’s statements in recent years became more and more markedly prognostic. This ‘futurological deformation’ was totally alien to ecology so long as it considered itself to be merely a particular area of biology. It must be clearly understood that this science has now come to lay claim to a total validity—a claim which it cannot make good. The more far-reaching its conclusions, the less reliable it is. Since no one can vouch for the accuracy of the enormous volume of material from every conceivable science on which its hypotheses are constructed, it must—precisely to the degree that it wishes to make global statements—confine itself to working syntheses. One of the best known ecological handbooks—Population, Resources, Environment by Paul and Anne Ehrlich—deploys evidence from the following branches of sciences either implicitly or explicitly: statistics, systems theory, cybernetics, games theory and prediction theory; thermodynamics, biochemistry, biology, oceanography, mineralogy, meterology, genetics; physiology, medicine, epidemology, toxicology; agricultural science, urban studies, demography; technologies of all kinds; theories of society, sociology and economics (the latter admittedly in a most elementary form). The list is not complete. It is hard to describe the methodological confusion that results from the attempt at a synthesis of this sort. If one starts from this theoretical position there can, obviously, be no question of producing a group of people who are competent to deal with it. From now on ecology is marginally relevant to everyone; and this, incidentally, is what makes the statements in this article possible.

What till recently was a marginal science has within a few years become the centre of bitter controversies. This cannot be explained merely by the snowballing effect of the mass media. It is connected with the central statement made by human ecology—a statement that refers to the future and is therefore at one and the same time prognostic and hypothetical. On the one hand, everyone is affected by the statement, since it relates to the existence of the species; on the other, no one can form a clear and final judgement on it because, in the last resort, it can only be verified or proved wrong in the future. This hypothesis can be formulated as follows: the industrial societies of this earth are producing ecological contradictions, which must in the foreseeable future lead to their collapse.

In contradistinction to other earlier theories of catastrophe this prognosis does not rest on linear, monocausal arguments. On the contrary, it introduces several synergetic factors. A very simplified list of the different strains of causality would look something like this:

1. Industrialization leads to an uncontrolled growth in world population. Simultaneously the material needs of that population increase. Even given an enormous expansion in industrial production, the chances of satisfying human needs deteriorate per capita.

2. The industrial process has up to now been nourished from sources of energy which are not in the main self-renewing: among these are fossil fuels as well as supplies of fissile material like uranium. In a determinable space of time these supplies will be exhausted; their replacement through what are basically new sources of energy (such as atomic fusion) is theoretically conceivable, but not yet practically realizable.

3. The industrial process is also dependent on the employment of mineral raw materials—above all of metals—which are not self-renewing either; their exploitation is advancing so rapidly that the exhaustion of deposits can be foreseen.